In General, Materials & Lighting

Best Practices: Grass in Architectural Design

Representing grass has always been a challenge in architectural graphics, especially for the average designer who does not specialize in developing computer generated graphics (CGI). The best we could do in the past was to apply a bump map and maximize the setting, so the ground did not look completely flat. Then, Enscape totally changed the game in early 2017 by automatically adding three-dimensional grass within their real-time photorealistic rendering engine. And now, it just got better, as we have been given control over the height and height variation of the blades of grass! This is sure to be a new fan favorite for anyone designing building façades, parks, roadways or bridges!

Any material in Revit, SketchUp, Rhino or ArchiCAD with the word “grass” in its name will render as a thick three-dimensional-looking grass in Enscape by default. Even in the small comparison images below, it is easy to see what a big different this makes. This article will cover the ins and outs of the grass feature in Enscape, including some incredible new developments! The focus of this article will be on Revit and SketchUp

Revit flat grass

Enscape 3D Grass

Here are a few images I have created which greatly benefit from realistic and natural looking grass. All three images where rendered with Enscape and have had no post-production edits.

Grass shown in a transportation project

Grass shown in a landscape architecture project

GRASS IN REVIT

Using Autodesk Revit, we can achieve amazing results in Enscape using various materials to define grass. Let’s look at how this works and what the options are.

Grass Height

The magic happens when Grass Rendering is ticked within the Enscape settings dialog and one or more Revit materials have the keywords “grass”, “short grass”, “tall grass” or “wild grass”. Here is an example of each grass style compared side-by-side.

Revit material with keyword ‘grass’ in name

Revit material with keyword ‘tall grass’ in name

Revit material with keyword ‘wild grass’ in name

Here is what happens based on keywords used:

  • Grass: Medium grass
  • Short Grass: Shorter grass
  • Tall Grass: Taller grass
  • Wild Grass: Taller grass with varying blade heights
Tip
The keywords are not case sensitive, but you cannot change the order, e.g. “grass tall” is not the same as “tall grass” to Enscape. I have already made this mistake myself!

Grass Color

Because Enscape samples the color or texture assigned to the material, we can achieve interesting results. I have been using this texture for a while as it has subtle variations in color, which translates nicely to Enscape’s 3D grass. It was acquired from a larger high-resolution aerial image. I set the texture size to 120’ square; the patterns are not obvious due to the scale.

Texture I often use for the grass material texture

Here are the results in Enscape… notice the color is not consistent, an effect that often occurs due to droughts. So, the result is more natural if this is the look you are going for.

Grass rendered using texture shown above

Grass rendered using texture shown above

A few grass types to study

Grass Types

Now let’s look at how we can create specific grass types. You will be happy to know it is easy. First, notice a few grass types shown in the image: Centipede, Bermuda, St. Augustine and Zoysia. I found this image by searching the internet for “grass types”. I then cropped the image down to just the desired grass type (no text or lines) and saved a separate image. Applying that new image, with a texture size of about 8-12” wide and 4-5” tall produced the results shown below. Of course, finding larger tileable samples would produce better results and look correct in Revit if ‘realistic view’ were ever used.

Here are the results of my ‘grass types’ study in Enscape…

Grass type study: Centipede

Grass type study: Bermuda

Grass type study: St. Augustine

Grass type study: Zoysia

Out of curiosity, let’s look at what the two default Revit grass materials look like in Enscape – these are the ones that install with the software. There is a big difference. The one actually called “grass” is way too dark. The other is better, but still a little off. And this will change with the lighting, so remember to consider the albedo .

Grass study: Revit’s default grass material

Grass study: Revit’s default ‘Plant’ material

With this, we can see the variety of options we have to represent grass in Revit. Some of the techniques offered in the next section on SketchUp can also be applied in Revit. However, Revit does not have the detailed sliders for height and height variation.

Tip
If the grass is poking through your floor or walk in Revit, add a Building Pad below the floor/walk to stamp out the top of the toposurface in that area.

GRASS IN SKETCHUP

When working in SketchUp we have all of the options just covered for Revit and a few more! In fact, because of the Enscape-centric material editor and ability to place custom proxy object some designers will export their Revit models to SketchUp to finish the rendering task there. For my SketchUp examples I downloaded the model Walled Garden with Rock Waterfall created by JBJDesigns .

Grass settings in the Material Editor

Notice in the Enscape Materials dialog the Type is set to Grass and we have two sliders; one for Height and another for Height Variation. You can quickly set you material type to grass via the dropdown menu. The grass settings are only visible if the type is set to grass. Use the Height slider to adjust how long your grass is. The Height Variation slider adds variation to the height and size of the grass blades. The higher the amount of height variation, the wilder your grass will look. If you would prefer a more uniform appearance, set the slider to a low value.

When setting the material via keyword, the type is automatically set to grass because the SketchUp material name has the word ”grass” in it. But, we can also manually change the name if needed. In this model, there were a few materials with the words “vegetation” and “grass” in the same name. Those materials default to Vegetation so I must either change the name or manually change the type… I did the latter.

Grass height (0,50,100) and variation set to zero

Sports Examples

If you design sports stadiums or athletics fields for educational institutions, you will be happy to know Enscape can produce extraordinary results for this application! I did a quick search, again on 3D Warehouse, and found a high quality model of the Gillette-Stadium created by Cleveland Rocks to explore this use case.

In this SketchUp model each grass color is a different material. All I did for each of these materials was make sure the type was set to grass and adjust the height and variation sliders to zero. And that was it! Just five minutes into opening this model and I was able to navigate a photorealistic model in real-time, even adjusting the time of day.

Various grass materials used to define sports field

Here is a close-up shot of the logo defined by several different grass colors.

Detailed view of logo defined with grass material

Thinking Outside the Box

In this last example I selected a carpet texture for the albedo, and the result is not too bad in Enscape! There are likely many ways in which this versatile material can be used. However, keep in mind it cannot currently be used on vertical surfaces.

Using grass to represent carpet, outdoor carpet in this case

Example: Using grass to represent carpet, outdoor carpet in this case

CONCLUSION

It’s truly exciting to see such dramatic results for grass in a real-time rendering engine, which also has a live link to our favorite 3D modeling environments. And if you think the grass is amazing in these still images, wait until you see it in virtual reality using the Oculus Rift, HTC Vive or Windows Mixed Reality devices. It is breathtaking, and very memorable for clients and stakeholders.

For more inspiration, be sure to check out the Enscape Visualization Gallery to see what other customers are doing. If you have yet to give Enscape a try, download the free trial today and check it out with Revit, SketchUp, Rhino and/or ArchiCAD. If you are a student, be sure to take advantage of the free student version

Dan Stine

Dan Stine
He is an Author, Blogger, Educator,
BIM Administrator and Wisconsin registered architect.
He works full-time at LHB - a 250 person full-service design firm.

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